Reliability Analysis And Optimization Of Kinematic Accuracy Of Conjugate Cam Weft Insertion Mechanism On High-speed Rapier Looms

Aiming at the problems of motion reliability of high-speed rapier loom and smoothness of weft yarn transfer,the conjugate cam weft insertion mechanism is taken as the research object.Based on the mechanism motion reliability theory,the weft insertion is studied from the aspects of kinematics,dynamics and component flexibility.The analysis and optimization method of mechanism motion accuracy reliability,discusses the mechanism of motion accuracy error and weft yarn transfer and its reliability improvement method.The main contents are as follows:(1)Starting from the multi-mechanism transmission system of the rapier weft insertion the motion reversal and design model of the cam mechanism,the articulated four-bar mechanism and the gear mechanism and the conjugate cam weft insertion mechanism composed of the series are established,and the kinematic characteristics of the sword belt are analyzed.The model of the movement law of the sword belt with improved trapezoidal law is established.The simulation results show that the error rates of the displacement,velocity and acceleration of the sword belt and the improved trapezoidal motion law are 0.6%,3.5%and 7%,respectively,from the convex contour error and the pressure angle.In the other way,the correctness of the conjugate cam weft insertion mechanism and the design model and its sword belt motion law are verified.(2)For the motion accuracy error of the weft insertion mechanism and the weft yarn transfor problem,the motion precision model of the conjugate cam mechanism with cam and hinged four-har and gear and its series connection is established to explore the multi-mechanism transmission.The system accuracy error distribution mechanism shows that the cam,hinged four-bar and gear set account for 48%,35%and 17%of the influence of the head displacement error respectively.Motion error and dynamic deformation may cause the weft yarn to be mishandled and improve.The cam roller meshing accuracy and the reduction of the gap at the transmission link can effectively improve the weft yarn transfer accuracy.(3)Considering the flexible characteristics of the sword belt in the weft insertion mechanism,the reliability model of the flexible sword belt motion accuracy is established,and the relatio nship between the elastic de fo rmation of the swo rd belt and the motion precision error is analyzed.The results show that the centroid of the sword belt fluctuates with the increase of the cam speed.The upper and lower fluctuations will increase the friction between the sword belt and the yarn,and at the same time increase the error of displacement,velocity and acceleration,leading to the failure of the weft yarn transfer;improving the ribbon material,increasing the stiffness of the sword belt and reducing the quality of the swo rd head can improve the accuracy of the sword head movement.Weft yarn transfer stability and reliability.(4)Establishing the calculation model of motion precision error of conjugate cam weft insertion mechanism with flexible members,researching the error distribution mecha nism of rigid mechanism tra is mission based on error compe nsation method,and considering the processing cost coeffic ie nt and tra ns mission ratio of rigid mechanism and the elastic modulus of sword belt The motion precision reliability optimization method of the conjugate cam weft insertion mechanism with other factors shows that the displacement error of the sword belt increases by about 10%under the rigid-flexible coupling,and the elastic deformation of the sword belt has little influence on the overall error of the transmission system;The total error of the imechanism is reduced by 17%,and the reliability of the mechanism is improved by about 2%.Increasing the processing and installation accuracy of the weft insertion mechanism and the stiffness of the member can effectively improve the accuracy of the well yarn transfer.